The present invention relates to a suction accumulator for a refrigeration system for separating liquid refrigerant from gaseous refrigerant, for storing the liquid refrigerant, and for providing a smooth flow of gaseous refrigerant to the suction line of a compressor More specifically, the present invention provides a suction accumulator of improved efficiency and reduced size as compared to prior art suction accumulators. Furthermore, the present invention provides a suction accumulator which is more economical to manufacture than prior art suction accumulators.
Closed loop refrigeration systems conventionally employ a refrigerant which is normally in the gaseous state wherein it may be compressed by means of a compressor. The refrigerant leaves the compressor at a relatively high pressure and is then routed through a condenser coil and an evaporator coil and back to the compressor for recompression. The refrigerant, under some circumstances such as startup of the refrigeration system, may be in its liquid state as it leaves the evaporator. Also, during certain running conditions, the evaporator may be flooded so that excess liquid refrigerant could enter the suction line and return to the compressor. If liquid refrigerant enters the suction side of the compressor, a "slugging" condition may occur whereby abnormally high pressures may result in the compressor which in turn may cause blown gaskets, broken valves, etc.
Accordingly, prior art sucticn accumulators have been provided which act as storage reservoirs for the liquid refrigerant and which prevent such liquid refrigerant from entering the compressor. Such prior art accumulators permit the liquid refrigerant to change to its gaseous state before entering the compressor. Numerous types of prior art accumulator structures have been provided such as, for instance, shown in U.S. Pat. Nos. 4,009,596; 4,182,136; 4,194,370; 4,194,371; and 4,208,887. In all of these suction accumulators, it is attempted to separate the gaseous refrigerant from the liquid refrigerant, to store the liquid refrigerant in a vessel, and to permit the gaseous refrigerant to flow through the vessel to an outlet and into the compressor suction port. Thus, the accumulator acts as a storage vessel for the liquid refrigerant which, in due course, evaporates to its gaseous state and is then permitted to enter the compressor. Conventionally, such accumulators will also provide a metering mechanism whereby the liquid refrigerant is metered into the outlet of the accumulator so that the flow of liquid refrigerant into the suction part of the compressor is regulated to prevent the aforementioned "slugging" problems.
Prior art accumulators have incorporated various types of deflectors or baffles to aid in separating the liquid refrigerant from the gaseous refrigerant. However, one problem with such prior art structures has been that the liquid refrigerant is not completely separated from the gaseous refrigerant so that some liquid refrigerant is allowed to enter the compressor suction inlet and thus resulting, under certain conditions, in the aforementioned "slugging" problems.
Another problem which has been encountered with such prior art suction accumulators has been that the pressure drop across the suction accumulator and in particular across the deflecting baffle of the suction accumulator is substantial. Such a pressure drop represents lost work and thus reduces the efficiency of the refrigeration system incorporating the suction accumulator which is, of course, undesirable.
A further problem with prior art suction accumulators has been that the inflowing refrigerant disturbs the liquid in storage and causes splashing of liquid into the outlet of the suction accumulator. Additionally, in some accumulators, the liquid in storage, at certain temperatures, has tended to separate into its oil and refrigerant components, thus causing a refrigerant-rich mixture to be supplied to the compressor and starving the compressor from lubricant. Such a condition could result in compressor bearing failures.
A still further problem with prior art suction accumulators has been their relatively large size It is preferable for an accumulator to be compact as, in certain applications, space is at a premium. Furthermore, Underwriter Laboratories specifies that for suction accumulator vessels larger than three inches in diameter a fusible plug is required thus resulting in a more costly structure. On the other hand, it has been difficult in prior art suction accumulators of three (3) inches or less in diameter accommodates to provide a large enough refrigerant mass flow rate. It is therefore desired to provide a suction accumulator which is smaller than three inches in diameter yet which accommodates a large mass flow rate. It is also desired to provide a suction accumulator with a simple yet effective pressure equalization system.
Yet another problem with prior art suction accumulators has been that they have been relatively expensive to construct. The prior art suction accumulators have generally been comprised of metal parts which needed to be assembled by soldering or brazing to form fluid tight seals. Thus, it is desired to provide a more economical suction accumulator which is less expensive to assemble than prior art suction accumulators.